U.S. patent application number 11/862429 was filed with the patent office on 2008-04-10 for optical element for a light-emitting diode, led arrangement and method for producing an led arrangement.
Invention is credited to Monika Rose, Sven Weber-Rabsilber, Alexander Wilm.
Application Number | 20080084694 11/862429 |
Document ID | / |
Family ID | 38738940 |
Filed Date | 2008-04-10 |
United States Patent
Application |
20080084694 |
Kind Code |
A1 |
Rose; Monika ; et
al. |
April 10, 2008 |
OPTICAL ELEMENT FOR A LIGHT-EMITTING DIODE, LED ARRANGEMENT AND
METHOD FOR PRODUCING AN LED ARRANGEMENT
Abstract
An optical element comprises a radiation exit face for a
light-emitting diode, said optical element being suitable for
producing a radiation characteristic that breaks rotational
symmetry, and a light-emitting diode comprising such an optical
element, and an LED arrangement comprising a plurality of
light-emitting diodes arranged on a carrier, wherein each of the
light-emitting diodes is associated with its own optical element,
which is arranged and configured such that a radiation
characteristic of the respective light-emitting diode is formed
with broken rotational symmetry, and wherein the optical elements
are similarly implemented.
Inventors: |
Rose; Monika; (Muenchen,
DE) ; Weber-Rabsilber; Sven; (Neutraubling, DE)
; Wilm; Alexander; (Regensburg, DE) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
38738940 |
Appl. No.: |
11/862429 |
Filed: |
September 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60860943 |
Nov 24, 2006 |
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11862429 |
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Current U.S.
Class: |
362/240 ;
257/E33.073; 362/257; 362/296.07; 362/308; 362/317; 362/326 |
Current CPC
Class: |
F21V 5/04 20130101; H01L
2224/73265 20130101; F21V 5/08 20130101; H01L 2224/48091 20130101;
F21W 2131/103 20130101; F21Y 2115/10 20160801; H01L 2224/48247
20130101; G02B 3/0043 20130101; F21K 9/00 20130101; F21Y 2105/10
20160801; G02B 3/00 20130101; H01L 2224/32245 20130101; G02B 3/0006
20130101; H01L 33/58 20130101; F21Y 2105/12 20160801; H01L
2224/48091 20130101; H01L 2924/00014 20130101; H01L 2224/73265
20130101; H01L 2224/32245 20130101; H01L 2224/48247 20130101; H01L
2924/00 20130101 |
Class at
Publication: |
362/240 ;
362/257; 362/296; 362/308; 362/311; 362/317; 362/326 |
International
Class: |
F21V 13/04 20060101
F21V013/04; F21V 5/00 20060101 F21V005/00; F21V 7/00 20060101
F21V007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2006 |
DE |
10 2006 047 233.0 |
Claims
1. An optical element comprising a radiation exit face for a
light-emitting diode, wherein said optical element is suitable for
producing a radiation characteristic that breaks rotational
symmetry.
2. The optical element as in claim 1, whose radiation exit face is
configured as elongate in plan.
3. The optical element as in claim 1, wherein the ratio of a
longitudinal extent (a) of said radiation exit face of said optical
element to a transverse extent (b) of said radiation exit face when
said radiation exit face is viewed in plan is 2:1 or greater.
4. The optical element as in claim 1, wherein the ratio of a
longitudinal extent (a) of said radiation exit face of said optical
element to a transverse extent (b) of said radiation exit face when
said radiation exit face is viewed in plan is 3:1 or greater.
5. The optical element as in claim 1, wherein the ratio of a
longitudinal extent (a) of said radiation exit face of said optical
element to a transverse extent (b) of said radiation exit face when
said radiation exit face is viewed in plan is 4:1 or greater.
6. The optical element as in claim 1, wherein said radiation exit
face of said optical element has, in a plan view of said radiation
exit face, at least two marked axes.
7. The optical element as in claim 6, wherein said axes are axes of
symmetry.
8. The optical element as in claim 6, wherein said radiation exit
face extends curvilinearly in sectional planes each of which is
spanned by an optical axis of said optical element and by one of
said marked axes.
9. The optical element as in claim 1, which is shaped as
ellipsis-like in a plan view of said radiation exit face.
10. The optical element as in claim 1, which is implemented as a
lens.
11. A light-emitting diode comprising a radiation exit side and an
optical element, wherein said optical element is arranged and
configured such that said light-emitting diode has a radiation
characteristic with broken rotational symmetry.
12. The light-emitting diode as in claim 11, which is specifically
configured with a radiation characteristic that breaks rotational
symmetry.
13. The light-emitting diode as in claim 11, wherein said optical
element is implemented as a lens.
14. The light-emitting diode as in claim 11, wherein said optical
element is implemented as a reflector.
15. The light-emitting diode as in claim 11, wherein said optical
element is formed by a combination of a lens and a reflector.
16. The light-emitting diode as in claim 11, which includes an LED
chip for generating radiation.
17. The light-emitting diode as in claim 11, which includes an LED
component, said LED component comprising said LED chip and a
housing and said LED chip being disposed in said housing.
18. The light-emitting diode as in claim 17, wherein said LED
component is implemented as surface-mountable.
19. The light-emitting diode as in claim 17, wherein said optical
element is formed by a portion of said housing that is configured
as reflective of the radiation generated in said LED chip.
20. The light-emitting diode as in claim 17, wherein said optical
element is formed by a prefabricated optical element attached to
said LED component.
21. The light-emitting diode as in claim 11, wherein said optical
element contains a synthetic material.
22. The light-emitting diode as in claim 21, wherein said optical
element contains a synthetic material from the group consisting of
thermoplastic, duroplastic and silicone.
23. The light-emitting diode as in claim 11, wherein said optical
element contains a resin.
24. The light-emitting diode as in claim 11, wherein said optical
element contains a resin from the group consisting of epoxy resin,
acrylic resin and silicone resin.
25. The light-emitting diode as in claim 11, wherein said optical
element is configured as elongated in a plan view of the radiation
exit side.
26. The light-emitting diode as in claim 25, wherein the ratio of
the longitudinal extent (a) of said optical element to the
transverse extent (b) of said optical element in a plan view of
said radiation exit side is 2:1 or greater.
27. The light-emitting diode as in claim 25, wherein the ratio of
the longitudinal extent (a) of said optical element to the
transverse extent (b) of said optical element in a plan view of
said radiation exit side is 3:1 or greater.
28. The light-emitting diode as in claim 25, wherein the ratio of
the longitudinal extent (a) of said optical element to the
transverse extent (b) of said optical element in a plan view of
said radiation exit side is 4:1 or greater.
29. The light-emitting diode as in claim 11, wherein a radiation
exit face of said light-emitting diode has, in a plan view of said
radiation exit face, at least two marked axes.
30. The light-emitting diode as in claim 29, wherein said axes are
axes of symmetry.
31. The light-emitting diode as in claim 11, wherein said optical
element is shaped as ellipsis-like in a plan view of said radiation
exit side.
32. The light-emitting diode as in claim 11, wherein said optical
element is implemented in accordance with claim 1.
33. An LED arrangement comprising a plurality of light-emitting
diodes arranged on a carrier, wherein each of said light-emitting
diodes is associated with its own optical element, which is
arranged and configured such that a radiation characteristic of the
respective said light-emitting diode is formed with broken
rotational symmetry.
34. The LED arrangement as in claim 33, wherein said carrier is a
connecting carrier having a plurality of connecting leads, and said
light-emitting diodes are electrically conductively connected to
said connecting leads.
35. The LED arrangement as in claim 33, wherein said optical
elements comprise similarly shaped radiation exit faces.
36. The LED arrangement as in claim 33, wherein said light-emitting
diodes are arranged on said carrier in the manner of grid
points.
37. The LED arrangement as in claim 33, wherein a direction of
longitudinal extent of said optical element of a light-emitting
diode or of a plurality of light-emitting diodes extends obliquely
to an edge of said carrier.
38. The LED arrangement as in claim 33, wherein said optical
elements are arranged on said carrier such that they are rotated
relative to one another with respect to their directions of
longitudinal extent.
39. The LED arrangement as in claim 33, wherein said optical
elements are arranged parallel to one another with respect to their
directions of longitudinal extent.
40. The LED arrangement as in claim 33, which includes optical
elements that are arranged parallel to one another and obliquely to
one another with respect to their directions of longitudinal
extent.
41. The LED arrangement as in claim 33, wherein said light-emitting
diodes are arranged such that the radiation characteristics of said
light-emitting diodes superimpose to yield a defined radiation
characteristic for the LED arrangement.
42. The LED arrangement as in claim 33, wherein said defined
radiation characteristic of said LED arrangement is formed by
rotating light-emitting diodes relative to one another.
43. The LED arrangement as in claim 41, wherein said defined
radiation characteristic of said LED arrangement is formed by
rotating light-emitting diodes relative to one another.
44. A method of configuring an LED arrangement having a plurality
of light-emitting diodes, comprising: a) defining a desired
radiation characteristic for the LED arrangement; b) preparing a
multiplicity of light-emitting diodes having similar radiation
characteristics, the radiation characteristic of each
light-emitting diode with a broken rotational symmetry; c)
determining a suitable number and a suitable arrangement of the
light-emitting diodes for the desired radiation characteristic; d)
arranging the previously determined suitable number of
light-emitting diodes in the previously determined arrangement on a
carrier for said LED arrangement; and e) finishing the LED
arrangement with the desired radiation characteristic.
45. The method as in claim 44, where the finished LED arrangement
comprises an LED arrangement comprising a plurality of
light-emitting diodes arranged on a carrier, wherein each of said
light-emitting diodes is associated with its own optical element,
which is arranged and configured such that a radiation
characteristic of the respective said light-emitting diode is
formed with broken rotational symmetry.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. 119(a) to
German Patent Application 10 2006 047 233.0 filed Oct. 4, 2006 and
also claims priority under 35 U.S.C. 119(e) to U.S. Provisional
Application No. 60/860,943 filed Nov. 24, 2006, the contents of
said applications are incorporated herein by reference.
TECHNICAL FIELD
[0002] This disclosure relates to an optical element for a
light-emitting diode (LED), a light-emitting diode comprising an
optical element, an LED arrangement comprising a plurality of
light-emitting diodes, and a method for producing an LED
arrangement.
BACKGROUND
[0003] To obtain different light distributions, LEDs are currently
used with optics adapted to specific situations. Every new lighting
application therefore has to have its own optic.
SUMMARY
[0004] Disclosed herein are optical elements for one or more
light-emitting diodes by means of which an LED arrangement having a
plurality of light-emitting diodes and a defined radiation
characteristic can be formed in a simplified manner. A
light-emitting diode comprising such an optical element and an LED
arrangement comprising a plurality of light-emitting diodes will
further be specified. A method that simplifies the production of an
LED arrangement having a defined radiation characteristic will also
be specified.
[0005] In one embodiment, an optical element for a light-emitting
diode is provided in which the radiation exit face is suitable for
producing a radiation characteristic that breaks rotational
symmetry. Such an optical element is particularly suitable for
light-emitting diodes that are arranged on a carrier in an LED
arrangement in cases where the LED arrangement is intended to have
a defined radiation characteristic.
[0006] A light-emitting diode in one embodiment comprises a
radiation exit side and an optical element, said optical element
being arranged and configured such that the light-emitting diode
has a radiation characteristic with broken rotational symmetry.
[0007] An LED arrangement in one embodiment comprises a plurality
of light-emitting diodes arranged on a carrier, wherein each of the
light-emitting diodes is associated with its own optical element,
which is arranged and configured such that a radiation
characteristic of the respective light-emitting diode is formed
with broken rotational symmetry, and wherein the optical elements
are similarly, particularly identically, implemented.
[0008] A radiation characteristic with broken symmetry,
particularly rotational symmetry, is to be understood in particular
as a radiation characteristic that deviates in a specified manner,
for example with reference to an optical axis of the optical
element, from a rotationally symmetrical radiation
characteristic.
[0009] In the present context, only one optic with a
non-radially-symmetrical radiation characteristic is needed.
Different light distributions can be obtained with an LED
arrangement by arranging individual or plural LEDs plus their
optics on the carrier such that they are rotated by an angle of
between 0.degree. and 90.degree., preferably greater than 0.degree.
and less than 90.degree.. The resulting light distribution is a
combination of the light distributions of the individual LEDs. The
angle of rotation between the individual LEDs plus optics can be
the same or different.
[0010] By suitably rotating the LEDs provided with an optical
element, and particularly by mounting them on the carrier in
correspondingly rotated fashion, different lighting problems can be
solved without having to newly adapt the optic to every situation.
The optical element can be implemented, for example, as a lens, a
reflector, or a combination of a lens and a reflector.
[0011] In particular, an extremely wide range of radiation
characteristics can be obtained with an LED arrangement composed of
LEDs equipped with similar optical elements, by arranging them such
that they are rotated with respect to one another. Hence, the key
advantage is that new light distributions can be obtained merely by
adjusting the rotation of the LEDs, without the need to design and
fabricate new optics. By suitably superimposing the respective
off-rotational-symmetry radiation characteristics of the individual
LEDs, the LED arrangement can be made to yield a defined radiation
characteristic in a simple and cost-effective manner.
[0012] A defined radiation characteristic could also be obtained by
developing an optical element specifically for the particular
lighting situation (for example a lens, a reflector), but the
radiation characteristic can also be varied in a simple manner via
the arrangement of the LEDs relative to one another on the
carrier.
[0013] The configuration of the carrier can also be used to
influence the light distribution. For example, a mirror element or
a plurality of mirror elements can be attached to or configured in
the carrier. Furthermore, the carrier can be configured as
flexible, so that the radiation characteristic of the LED
arrangement can be varied by suitably bending the carrier.
[0014] The features described hereinafter with regard to an optical
element and a light-emitting diode are applicable respectively to
at least one optical element and at least one light-emitting diode
of the LED arrangement, preferably respectively to all the optical
elements and to all the light-emitting diodes of the LED
arrangement. The use of similar, particularly identical, optical
elements and light-emitting diodes simplifies the adaptation of the
LED arrangement to the defined radiation characteristic.
[0015] In a preferred configuration, the radiation exit face of the
optical element is configured as elongate in plan.
[0016] In particular, the ratio of a longitudinal extent (a) of the
radiation exit face (40) of the optical element (4) to a transverse
extent (b) of the radiation exit face (40) in a plan view of the
radiation exit face is 1.5:1 or greater, preferably 2:1 or greater,
particularly preferably 3:1 or greater, at most preferably 4:1 or
greater.
[0017] The greater the ratio between the longitudinal extent and
the transverse extent, the more the radiation characteristic is
able to deviate from a rotationally symmetrical shape.
[0018] In a preferred configuration, the radiation exit face of the
optical element has, in a plan view of the radiation exit face, at
least two marked axes. The marked axes can in particular be
perpendicular to each other.
[0019] In sectional planes that are each spanned by the optical
axis and one of the marked axes, the radiation exit face preferably
extends curvilinearly in each case.
[0020] Further preferably, the marked axes are axes of symmetry.
The radiation exit face can thus be mirror-symmetrical to the
marked axes.
[0021] In a further preferred configuration, the optical element,
particularly the radiation exit face, has an ellipsoid-like shape
when the radiation exit face is viewed in plan. A
rotational-symmetry-free radiation characteristic for the optical
element is easier to obtain in this way.
[0022] The optical element preferably contains a synthetic
material, particularly a synthetic material from the group
consisting of thermoplastic, duroplastic and silicone.
[0023] Alternatively or supplementarily, the optical element can
contain a resin, particularly a resin from the group consisting of
epoxy resin, acrylic resin and silicone resin.
[0024] Such an optical element is easier and less expensive to make
than a glass lens, for example.
[0025] The optical element is further preferably implemented such
that it can be attached to an LED via a material-locking
connection, such as an adhesive bond. Alternatively or
supplementarily, the optical element can be provided for mechanical
connection to an LED, for example via a plug-in or snap-in
connection, and can be equipped with suitable fasteners. The
optical element can in particular be implemented as an attachment
optic, for example an attachment lens.
[0026] In a preferred configuration, the LED is specifically
configured with a radiation characteristic that breaks rotational
symmetry. An optical element having at least one of the described
features is particularly suitable for this purpose.
[0027] In particular, to produce a radiation characteristic that
has no rotational symmetry, the optical elements of the individual
LEDs are preferably configured as elongate in a plan view of their
respective radiation exit sides.
[0028] In addition, the light-emitting diode expediently comprises
at least one LED chip for generating radiation. The LED chip can,
in particular, comprise an active region provided for generating
radiation. The active region preferably contains a III-V compound
semiconductor. III-V compound semiconductors are distinguished in
particular by a high attainable internal quantum efficiency.
[0029] Radiation generated in the light-emitting diode,
particularly in the LED chip, during operation expediently exits
from the radiation exit side of the light-emitting diode through
the radiation exit face of the optical element.
[0030] In a further preferred configuration, the light-emitting
diode includes an LED component, said LED component comprising the
LED chip and a housing. The LED chip is preferably disposed in the
housing.
[0031] In a further preferred configuration, the optical element is
formed by a portion of the housing that is configured to be
reflective of the radiation generated in the LED chip. For example,
the LED chip can be disposed in a cavity in the housing, with a
wall of the cavity forming a reflector.
[0032] Alternatively or supplementarily, the optical element can be
formed by a prefabricated optical element, for example an
attachment lens, which is attached to the LED component,
particularly to the housing.
[0033] Particularly preferably, the LED component is implemented as
a surface-mountable device (SMD, surface mounted device). A
component implemented in this way can be attached to a carrier in a
simple manner. Whereas with a component of through-hole design,
when the part is rotated relative to the carrier it is necessary at
the very least to change the position of a recess in the carrier,
an SMD component can be rotated relative to the carrier in a simple
manner.
[0034] In a preferred configuration, the carrier of the LED
arrangement is a connecting carrier having a plurality of
connecting leads, the light-emitting diodes being electrically
conductively connected to said connecting leads. The connecting
carrier can be implemented as rigid or flexible. The connecting
carrier can be a circuit board, for example. Carrying this further,
the circuit board can be implemented as a metal-core circuit board
(MCPCB, metal core printed circuit board).
[0035] The optical elements of the light-emitting diodes of the LED
arrangement preferably have similarly shaped, particularly
identical, radiation exit faces. The carrier can thus be fitted
with a multiplicity of similar or identical light-emitting diodes,
thereby simplifying the production of the LED arrangement.
[0036] The light-emitting diodes can be arranged on the carrier in
the manner of grid points, for example in the form of a matrix or
in the form of a honeycomb pattern.
[0037] In a preferred improvement, a direction of longitudinal
extent of the optical element of a light-emitting diode or of a
plurality of light-emitting diodes extends obliquely to an edge of
the carrier. This makes it easier to obtain uniform radiation from
the LED arrangement, particularly including in the corner regions
of the carrier. An undesirable drop in the emitted radiant power
toward the edge of the carrier, particularly in corner regions of
the carrier, can thus be avoided or at least reduced in a simple
manner.
[0038] In a further preferred configuration, optical elements are
arranged rotated relative to one another with respect to their
direction of longitudinal extent in a plan view of the carrier,
particularly rotated by an angle of more than 0.degree. and less
than or equal to 90.degree.. Rotating the optical elements relative
to one another provides a simple way of matching the radiation
characteristic of the LED arrangement to a defined radiation
characteristic.
[0039] In a preferred improvement, the LED arrangement includes
optical elements that are arranged parallel to one another and
optical elements that are arranged obliquely to one another. For
example, the LED arrangement can comprise plural groups of optical
elements, the optical elements in each group being arranged
parallel to one another and the directions of longitudinal extent
of different groups being arranged rotated with respect to one
another.
[0040] Further preferably, the light-emitting diodes are arranged
such that the radiation characteristics of the light-emitting
diodes superimpose to yield a defined radiation characteristic of
the LED arrangement.
[0041] In a further preferred improvement, the defined radiation
characteristic of the LED arrangement can be formed by rotating
light-emitting diodes relative to one another. Merely rotating the
light-emitting diodes relative to one another can be sufficient for
this purpose. The positions of the light-emitting diodes on the
carrier can thus be kept unchanged or substantially unchanged in
order to form a defined radiation characteristic. In other words,
the orientation of the optical elements, for instance in relation
to the direction of longitudinal extent of the radiation exit face,
represents an additional degree of freedom, besides the focal-point
position of the light-emitting diode, that is available for
influencing the radiation characteristic of the LED arrangement
during its production.
[0042] In a variant configuration, the LED arrangement has an axis
of symmetry, particularly preferably two axes of symmetry. The
light-emitting diodes can be arranged symmetrically, particularly
axially symmetrically, relative to this axis of symmetry or these
axes of symmetry. A defined symmetrical radiation characteristic
can thus be obtained for the LED arrangement in a simplified
manner. For example, the light-emitting diodes in the corner
regions of the carrier can be arranged symmetrically to one
another, said light-emitting diodes being rotated relative to the
light-emitting diodes in the inner region of the carrier.
[0043] Depending on the defined radiation characteristic of the LED
arrangement, the light-emitting diodes can also be arranged in a
manner that deviates from a symmetrical arrangement.
[0044] According to an exemplary embodiment of a method of
configuring an LED arrangement comprising a plurality of
light-emitting diodes, a desired radiation characteristic is
defined for the LED arrangement. A multiplicity of light-emitting
diodes with similar radiation characteristics is prepared, with the
radiation characteristic of each light-emitting diode exhibiting
broken rotational symmetry. A suitable number and a suitable
arrangement of the light-emitting diodes for the desired radiation
characteristic are determined. The previously determined suitable
number of light-emitting diodes is arranged in the previously
determined arrangement on a carrier for the LED arrangement, and
the LED arrangement is finished with the desired radiation
characteristic.
[0045] An LED arrangement having a defined radiation characteristic
can be produced more simply in this way. In particular, the desired
radiation characteristic can be set or at least approximated by
rotating the light-emitting diodes relative to the carrier, and
particularly also relative to one another. This eliminates the need
for the onerous process of designing and implementing an optic for
the plurality of light-emitting diodes that is specific to the
application concerned and depends in each case on the defined
radiation characteristic.
[0046] The described method is particularly suitable for the
production of a described LED arrangement, so features described in
connection with the LED arrangement can also be applied to the
method and vice versa.
[0047] Additional aspects, features, and advantages follow from the
following description of the exemplary embodiments made in
conjunction with the drawings.
DESCRIPTION OF DRAWINGS
[0048] FIGS. 1A to 1C show a first exemplary embodiment of an LED
arrangement in a schematic oblique view in FIG. 1A, a schematic
plan view in FIG. 1B and a schematic detailed sectional view in
FIG. 1C,
[0049] FIG. 2 shows a second exemplary embodiment of an LED
arrangement in a schematic plan view,
[0050] FIG. 3 shows a third exemplary embodiment of an LED
arrangement in a schematic plan view, and
[0051] FIG. 4 shows a second exemplary embodiment of an LED
arrangement in a schematic plan view.
[0052] Like, similar, and like-acting elements are provided with
the same respective reference characters in the figures. The
figures are all schematic representations and therefore are not
necessarily true to scale. Rather, small elements may be depicted
as exaggeratedly large for purposes of better understanding.
DETAILED DESCRIPTION
[0053] The first exemplary embodiment of an LED arrangement 1,
illustrated schematically in FIGS. 1A to C, includes a carrier
2.
[0054] Attached to the carrier 2 is a plurality of light-emitting
diodes 3, preferably three or more light-emitting diodes,
particularly preferably six or more light-emitting diodes (nine
light-emitting diodes are depicted by way of example). The carrier
2 can be rigid or flexible, and is further preferably implemented
as a connecting carrier, for example as a circuit board, preferably
a printed circuit board (PCB). Carrying this further, the
connecting carrier can be implemented as a metal-core circuit
board. The light-emitting diodes 3 are expediently configured as
surface-mountable components and, on the connecting carrier, are
electrically conductively connected to connecting leads, for
example by gluing or soldering. This simplifies the mounting of the
light-emitting diodes.
[0055] Specular or reflective elements that can be used to further
influence the radiation characteristic of the LED arrangement (not
explicitly illustrated) can additionally be configured in or on the
carrier 2.
[0056] The radiation characteristic of the LED arrangement 1 can
further be adjusted, particularly in the case of a flexible carrier
2, by curving the carrier 2.
[0057] The LED arrangement preferably includes light-emitting
diodes for generating mixed-color light, particularly light that
appears white to the human eye, for example in three primary colors
such as red, green and blue.
[0058] Each of the light-emitting diodes 3 comprises a similar
optical element 4 and an LED component 5. The optical element 4 is
implemented as a separately prefabricated optical element,
particularly as a lens, which is attached to the LED component 5.
Where appropriate, the optical element can also be implemented as a
reflector integrated into the LED component or as a combination of
such a reflector with a lens (not shown). The present optical
element 4 has a radiation exit face 40.
[0059] The optical element 4, as viewed from outside the element,
can be configured with a radiation exit face 40 that is convexly
curved, preferably continuously.
[0060] The optical element further has a first marked axis 45 and a
second marked axis 46. Each radiation exit face can in particular
be implemented as curved in sections taken along these marked
axes.
[0061] The optical element 4 is implemented such that each of the
light-emitting diodes 3 has a non-rotationally-symmetrical
radiation characteristic.
[0062] The radiation characteristic can be determined, for example,
by the dependence of the intensity of the radiation from the
light-emitting diode on the angle formed with the optical axis. The
optical axis 7 preferably extends through an LED chip 6 of the
particular light-emitting diode 3. Particularly preferably, the
optical axis 7 extends through a central region of radiation exit
face 40. The optical axis can in particular extend perpendicularly
to the surface of the LED chip 6 facing toward the optical element
4, and preferably perpendicularly to the radiation exit face
40.
[0063] The present optical element 4 is implemented as elongate,
for example with a radiation exit face 40 that is ellipsoidal in
plan. The long principal axis a can be 1.5 times or more as long,
preferably twice or more as long, particularly preferably three
times or more as long, at most preferably four times or more as
long, than the short principal axis b of the ellipsis.
[0064] With the use of such an optical element 4, a radiation
characteristic that has no rotational symmetry with respect to the
optical axis 7 can be formed by beam-shaping or refracting the
radiation generated in the LED chip 6. The LED chip expediently has
an active region for generating radiation. Moreover, the LED chip,
particularly the active region, contains a III-V semiconductor
material. III-V semiconductor materials are particularly suitable
for generating radiation in the ultraviolet
(In.sub.xGa.sub.yAl.sub.1-x-yN) through the visible
(In.sub.xGa.sub.yAl.sub.1-x-yN especially for blue to green
radiation, or In.sub.xGa.sub.yAl.sub.1-x-yP, especially for yellow
to red radiation) to the infrared (In.sub.xGa.sub.yAl.sub.1-x-yAs)
regions of the spectrum. In each of the foregoing cases,
0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1 and x+y.ltoreq.1,
particularly with x.noteq.1, y.noteq.1, x.noteq.0 and/or y.noteq.0.
In addition, advantageously high internal quantum efficiencies can
be achieved when radiation is generated using III-V semiconductor
materials, particularly from the aforesaid material systems. The
optical element preferably contains a synthetic material,
particularly a synthetic material from the group consisting of
thermoplastic, duroplastic and silicone.
[0065] Alternatively or supplementarily, the optical element can
contain a resin, particularly a resin from the group consisting of
epoxy resin, acrylic resin and silicone resin.
[0066] An elongate, particularly ellipsoid-like, illuminance
distribution can therefore be produced on a to-be-illuminated
surface extending parallel to the carrier 2 if said surface is
illuminated by means of a single light-emitting diode 3.
[0067] Despite the breaking of rotational symmetry, the radiation
characteristic of the light-emitting diode can extend axially
symmetrically to the optical axis. The illuminance distribution of
the individual light-emitting diode on the surface to be
illuminated then does not exhibit any islands of increased radiant
power located away from the optical axis.
[0068] The radiation characteristic of the LED arrangement 1 is
obtained by superimposing the radiation emitted by the individual
light-emitting diodes 3.
[0069] If some or all of the optical elements 4 are arranged with
the direction of longitudinal extent (for example, long main axis
a) oblique, i.e. at an angle different from 0.degree. and in
particular also different from 90.degree., to an edge 20 of the
carrier 2, then defined radiation characteristics for the LED
arrangements, and thus also a defined illuminance distribution on a
surface to be illuminated, can be obtained in a simplified
manner.
[0070] The individual optical elements 4 are arranged rotated with
respect to the carrier 2, which in particular is planar. The
direction of rotation preferably extends azimuthally to the optical
axis 7.
[0071] According to FIGS. 1A and 1B, the light-emitting diodes 3
are arranged grouped in a polygon, particularly a rectangle. The
light-emitting diodes 3 are preferably arranged in a matrix-like
manner. In deviation therefrom, another, preferably regular,
arrangement, for example in a honeycomb pattern, may also be
expedient.
[0072] The optical elements 4 of the corner light-emitting diodes
are each rotated in their direction of longitudinal extent relative
to the direction of longitudinal extent of the optical element 4 of
an adjacent light-emitting diode (cf., for example, intermediate
angle 8). The inner optical elements 4 are oriented in parallel in
the longitudinal direction, particularly parallel to the carrier
edge 20.
[0073] Diagonally opposite optical elements are arranged with their
longitudinal directions parallel. Any decrease in the illuminance
distribution toward the edges of the surface to be illuminated by
the LED arrangement 1 can be reduced in this way. Homogeneous
illumination of a surface is thereby simplified.
[0074] FIG. 1C is a schematic sectional view of a detail of the
lighting arrangement illustrated in FIGS. 1A and 1B, showing only
one light-emitting diode 3 arranged on the carrier 2.
[0075] The light-emitting diode 3 includes an LED component 5
comprising a housing 55. The LED chip 6 is disposed in a cavity 56
of the housing 55. A wall 57 of the cavity 56 forms a reflector.
Such a wall is implemented as reflective of the radiation generated
in the LED chip. To increase reflection, the wall can be provided
with a coating if necessary. Radiation generated in the LED chip
can be reflected from the wall 57 and deflected in the direction of
the radiation exit face 40 of the optical element.
[0076] The reflector configured in the LED component 5 can be
implemented as rotationally symmetrical to the optical axis. A
radiation characteristic that has no rotational symmetry can also
be formed by means of the correspondingly shaped optical element 4.
However, the reflector can also be shaped so as to result in, or at
least be conducive to, a radiation characteristic that breaks
rotational symmetry. For example, the reflector can have a basic
shape in plan that deviates from a circular shape, for instance an
elliptical shape. An optic with a radiation characteristic that
breaks rotational symmetry can therefore also be obtained by means
of a reflector or a combination of a reflector with a lens.
[0077] The LED component comprises a contact lead 51 and a further
contact lead 52, each of which is electrically conductively
connected respectively to a terminal area 21 and to a further
terminal area 22 on the carrier 2, for example via an electrically
conductive connecting means 59, such as a solder. The contact leads
51, 52 are electrically conductively connected to the LED chip, it
being possible to establish the electrically conductive connection
of contact lead 51 by means of a bond wire 53.
[0078] Particularly to protect against external influences, such as
moisture, the LED chip 6 and, if present, the bond wire 53 can be
embedded in an encapsulant 56.
[0079] In FIG. 1C, optical element 4 is attached to LED component
5, particularly to housing 55, by means of an adhesive layer 9.
Alternatively or additionally, the optical element can also be
configured for mechanical connection, for example a plug-in,
snap-in or snap-on connection.
[0080] Furthermore, in deviation from the illustrated exemplary
embodiment, the optical element can project at least regionally
outward laterally beyond the LED component 5, particularly beyond
the housing 55.
[0081] In a method for producing an LED arrangement 1, a desired
radiation characteristic can first be defined for the LED
arrangement. A multiplicity of light-emitting diodes 3 having
similar radiation characteristics can be prepared, with the
radiation characteristic of each of the light-emitting diodes
exhibiting a broken rotational symmetry. A suitable number and a
suitable arrangement of the light-emitting diodes for the desired
radiation characteristic can then be determined. For example, by
increasing the number of light-emitting diodes, it is possible to
increase the overall radiant power of the LED arrangement. The
previously determined suitable number of light-emitting diodes, in
the previously determined arrangement, can be disposed on and in
particular attached to a carrier 2 for the LED arrangement. The
radiation characteristic can be adjusted in particular by suitably
orienting the light-emitting diodes 3, i.e. by rotating the
light-emitting diodes 3 relative to one another or relative to a
carrier edge 20. The light-emitting diodes 3 can be attached to the
carrier 2, for example by soldering or gluing, in the provided
position and orientation.
[0082] LED arrangements produced and finished according to this
method can be implemented as described in connection with FIGS. 1A
to 1C and 2 to 4.
[0083] LED arrangements whose radiation is matched to a defined
desired radiation characteristic can also be produced in a simple
manner by the described method.
[0084] FIG. 2 shows a second exemplary embodiment of an LED
arrangement. This second exemplary embodiment is basically the same
as the above-described first exemplary embodiment. It differs
therefrom in that the light-emitting diodes 3 are arranged in a
matrix-like manner, with the optical elements 4 of the
light-emitting diodes 3 arranged in respective columns and with
mutually parallel directions of longitudinal extent. In addition,
the directions of longitudinal extent of the optical elements of
light-emitting diodes in adjacent columns are oblique to each other
in each case.
[0085] The directions of longitudinal extent of the light-emitting
diodes 3 in the outer columns extend parallel to one another. The
directions of longitudinal extent of the light-emitting diodes in
the center column extend parallel to a carrier edge 20 of the
carrier 2.
[0086] FIG. 3 shows a third exemplary embodiment of an LED
arrangement. This third exemplary embodiment is basically the same
as the second exemplary embodiment described in connection with
FIG. 2. In contrast to the second exemplary embodiment, here all
the optical elements 4 are arranged obliquely to the carrier edge
20, with the directions of longitudinal extent of all the optical
elements extending parallel to one another. The directions of
longitudinal extent of the optical elements 4 in adjacent columns
therefore extend parallel to each other in each case.
[0087] FIG. 4 shows a fourth exemplary embodiment of an LED
arrangement. This fourth exemplary embodiment is basically the same
as the second exemplary embodiment described in connection with
FIG. 2. In contrast to the second exemplary embodiment, here the
optical elements 4 are arranged in rows with mutually parallel
directions of longitudinal extent, with the directions of
longitudinal extent of adjacent rows extending obliquely to each
other. The directions of longitudinal extent of the outer rows
extend parallel to each other.
[0088] Naturally, another arrangement and/or orientation of the
directions of longitudinal extent of the optical elements 4 may be
appropriate for the light-emitting diodes, depending on the defined
radiation characteristic of the LED arrangement. A defined
radiation characteristic of the LED arrangement 1 can be obtained
in a simple manner by combining a suitable number of light-emitting
diodes 3 and a suitable oblique position for the elongate optical
elements 4 relative to one another and/or to the carrier edge
20.
[0089] Additional embodiments are within the scope of the following
claims.
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